Prevalence, Morphology, and Genetic Relationship of Sarcocystis species in Naturally Infected Sheep

Abstract

Sarcocystosis is a parasitic disease caused by intracellular coccidian protozoan belonging to the genus Sarcocystis. While inducing substantial economic losses in host animals as well as neurological disorders and abortions, limited knowledge exists regarding the Sarcocystis species that infect sheep and their potential impact on mutton quality and human health owing to the presence of microscopic Sarcocystis in the flesh. The objective of the present study was to investigate the prevalence, morphological characteristics, and genetic relationship of Sarcocystis species identified during routine meat inspections in naturally infected sheep. A macroscopic infection rate of 0.35% was recorded, primarily involving Sarcocystis gigantea and Sarcocystis medusiformis, with a microscopic infection rate of 55.9%, and a high prevalence in diaphragmatic (72%), esophageal (57.1%), and cardiac (31.4%) muscles. Molecular analysis of Cytochrome oxidase COX1 and 18S rRNA genes highlighted high genetic similarity between S. tenella isolates from Egypt and other regions, including Spain, Norway, and China, with genetic identities ranging from 96.82% to 100%. Phylogenetic analysis indicated minimal host-specific variation, as Egyptian sheep and goat isolates clustered together. S. arieticanis also showed close genetic relationship with isolates from diverse locations. These findings demonstrate broad genetic consistency within S. tenella and S. arieticanis populations across geographic regions, suggesting limited regional variation and providing insights into Sarcocystis species phylogenetics in small ruminants. The findings of this study revealed a wide array of Sarcocystis species that infect livestock, highlighting the need for enhanced surveillance and control measures to mitigate their impact on animal health and food safety.